title: With respect to coefficient of linear thermal expansion, bacterial vegetative cells and spores resemble plastics and metals, respectively.
abstract: BACKGROUND
  If a fixed stress is applied to the three-dimensional z-axis of a solid material, followed by heating, the amount of thermal expansion increases according to a fixed coefficient of thermal expansion. When expansion is plotted against temperature, the transition temperature at which the physical properties of the material change is at the apex of the curve. The composition of a microbial cell depends on the species and condition of the cell; consequently, the rate of thermal expansion and the transition temperature also depend on the species and condition of the cell. We have developed a method for measuring the coefficient of thermal expansion and the transition temperature of cells using a nano thermal analysis system in order to study the physical nature of the cells.
  
  
  RESULTS
  The tendency was seen that among vegetative cells, the Gram-negative Escherichia coli and Pseudomonas aeruginosa have higher coefficients of linear expansion and lower transition temperatures than the Gram-positive Staphylococcus aureus and Bacillus subtilis. On the other hand, spores, which have low water content, overall showed lower coefficients of linear expansion and higher transition temperatures than vegetative cells. Comparing these trends to non-microbial materials, vegetative cells showed phenomenon similar to plastics and spores showed behaviour similar to metals with regards to the coefficient of liner thermal expansion.
  
  
  CONCLUSIONS
  We show that vegetative cells occur phenomenon of similar to plastics and spores to metals with regard to the coefficient of liner thermal expansion. Cells may be characterized by the coefficient of linear expansion as a physical index; the coefficient of linear expansion may also characterize cells structurally since it relates to volumetric changes, surface area changes, the degree of expansion of water contained within the cell, and the intensity of the internal stress on the cellular membrane. The coefficient of linear expansion holds promise as a new index for furthering the understanding of the characteristics of cells. It is likely to be a powerful tool for investigating changes in the rate of expansion and also in understanding the physical properties of cells.
authors.affiliation: Research Laboratories for Beverages, Kirin Company, Limited, Technovillage 3F, 1-17-1 Namamugi, Tsurumi-ku, Yokohama 230-8628, Japan. chita-mbrc@u07.itscom.net.
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Akinori
authors.initials: A
authors.lastname: Kogure
authors.forename: Takenao
authors.initials: T
authors.lastname: Fujii
authors.forename: Ryohei
authors.initials: R
authors.lastname: Kokawa
authors.forename: Keiji
authors.initials: K
authors.lastname: Deuchi
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Kuwana
authors.forename: Hiromu
authors.initials: H
authors.lastname: Takamatsu
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry* / Q000648:ultrastructure; D001696:Biomechanical Phenomena; D002462:Cell Membrane / Q000737:chemistry / Q000648:ultrastructure; D003600:Cytosol / Q000737:chemistry / Q000648:ultrastructure; D004926:Escherichia coli / Q000737:chemistry* / Q000648:ultrastructure; D008670:Metals / Q000737:chemistry; D008954:Models, Biological; D044367:Phase Transition; D010969:Plastics / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000648:ultrastructure; D013171:Spores, Bacterial / Q000737:chemistry* / Q000648:ultrastructure; D013211:Staphylococcus aureus / Q000737:chemistry* / Q000648:ultrastructure; D013696:Temperature
chemical_list: D008670:Metals; D010969:Plastics